Actinide/beryllium neutron sources with reduced dispersion characteristics

Abstract

Neutron source comprising a composite, said composite comprising crystals comprising BeO and AmBe13, and an excess of beryllium, wherein the crystals have an average size of less than 2 microns; the size distribution of the crystals is less than 2 microns; and the beryllium is present in a 7-fold to a 75-fold excess by weight of the amount of AmBe13; and methods of making thereof.

Description

REFERENCE TO PRIOR APPLICATION[0001]This application claims the benefit of priority to U.S. Provisional Patent Application 61 / 242,237, filed Sep. 14, 2009, and incorporated herein in its entirety.STATEMENT OF FEDERAL RIGHTS[0002]The United States government has rights in this invention pursuant to Contract No. DE-AC52-06NA25396 between the United States Department of Energy and Los Alamos National Security, LLC for the operation of Los Alamos National Laboratory.FIELD OF THE INVENTION[0003]The present invention relates to composites comprising BeO and AmBe13, in an excess of Be metal, having reduced dispersion characteristics and which are suitable for use in neutron sources, and methods of making thereof.BACKGROUND OF THE INVENTION[0004]Neutron sources are used in a variety of applications, including oil and natural gas exploration. Currently available commercial neutron sources contain finely divided powders comprising a radioactive material, e.g., 241AmO2, and beryllium metal, wh...

AI Technical Summary

Benefits of technology

[0006]The present invention meets the aforementioned needs by providing a neutron source comprising a Be / BeO / AmBe13 composite. The composite comprises crystals comprising BeO and AmBe13, in an excess of Be metal. The composite is a solid monolith engineered for strength rather than a mixture of powders, and thus exhibits decreased dispersibility. The crystals have a size of less than 2 μm, and are monodisperse, meaning that the size distribution is narrow. These characteristics impart desirable qualities to the composite, including hardness and tensile strength which allow for more robust sources. The composite is obtained by a novel process which utilizes induction heating to perform rapid heating and cooling. The composite of the present invention is not easily dispersed, and allows for more efficient and complete cleanup in the event of an accident. The source of the present invention further is more efficient than currently available sources, which means that less 241Am is required to achieve the same neutron output.

[0007]AmBe neutron sources provide a portable, tough, continuous, and reliable source of neutrons independent of a reactor or a neutron generator. 241AmO2 and Be mixtures create a neutron source via an “alpha-N” reaction (shorthand representation 9Be(α,N)12C). 241Am has a half-life of 432 years, and this relatively high specific activity provides good neutron source efficiency, useful neutron flux ranges, and steady neutron output for years in an AmBe source. Be has the highest neutron yield from (α,N) reaction of any element, although even Be does require many thousands of alpha particles to produce one neutron.

Problems solved by technology

In some instances, neutron sources may be lost or damaged during the process.

In order to prevent accidental dispersion, the powdered material is encased in multiple welded capsules, however, the capsules are not always strong enough to prevent accidental dispersion.

Whether accidental or intentional, once a powdered substance is dispersed, containment and cleanup become difficult (if not impossible) and expensive.

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